The Trans-Pacific Partnership, the most expansive trade agreement in history, is being hailed among its dozen member governments for unifying a market encompassing 40 percent of the global economy with $30 trillion total output. But the pact's implementation is not yet assured.

After the secrecy during the negotiating process, politicians, special interest groups and the public in the 12 TPP countries will soon get to analyze the details when the entire document is published.

Some are going to see items they do not like. And that will increase the pressure on legislators weighing whether to support it. If all of the participating countries do not ratify it within two years then six original signatories which account for 85 percent of the bloc's gross domestic product must ratify it. The math means approval by the United States is essential along with either Canada or Japan.

US approval required

Already there is considerable opposition expressed by some powerful U.S. senators, including those in President Barack Obama’s Democratic Party. Former secretary of state and now Democratic presidential candidate Hillary Clinton is among those opposing the TPP.

The president, before signing the pact, has to wait at least 90 days after officially informing Congress of the agreement -- some expect that to occur within days. During that window the full text must be public for at least 60 days. A Congressional vote might not occur until sometime next year amid the distractions of the 2016 presidential election campaigning.

“I could imagine that if the U.S. cannot or will not or is unable to implement the agreement that the others might decide to move ahead anyway and basically do a new version of this agreement without the United States,” predicts Deborah Elms, a TPP proponent who is the executive director of the Singapore-based Asia Trade Center.

The TPP's fate in Canada could hinge on the outcome of federal elections on October 19.

There is also significant opposition to the TPP in Australia and New Zealand, although it is likely to gain legislative approval in both countries, according to Asia Trade Center's Elms.

“They believe that the Americans got far more of what they wanted than Australia or New Zealand got,” Elms, in Kuala Lumpur, told VOA.

New Zealand’s Labor Party — currently not part of the government — is also upset with a TPP provision prohibiting foreign investment in land and housing.

And Chile is another country where there could be strong congressional opposition, due to concerns about affordable access to medicines.

Broad support in Japan, Vietnam

Eventual ratification is seen as all but assured in Japan.

It will be examined by both houses of Japan’s parliament, and the government is considering holding an extra session through early next year, although it is uncertain if deliberation on the TPP will be finished. Significant moves by Japan on the agriculture front will have some farmers’ groups fighting approval.

In Malaysia, opposition lawmaker Charles Santiago has criticized the TPP as “one of the most dangerous trade pacts when it comes to access to affordable medicine, particularly in the developing world.” He told VOA that Malaysia’s government has promised to follow the lead of the parliament's consensus. But it has the power to approve the pact even if the majority of lawmakers oppose it.

“They could, because technically the constitution allows the cabinet to sign on to any trade agreement, which they have done all this while. But because of the pressure from civil society, from trade unions, from professional groups including small and medium industries, I think the government said 'look, we need a buy-in. And if parliament doesn't support the idea of this agreement, then we will not support it,'” Santiago said.

Vietnam stands to be one of the biggest beneficiaries from the Pacific accord. The country's economy, by 2025, will be 11 per cent bigger than without the trade deal, with exports under TPP forecast to increase 28 per cent, according to a recent report by the Eurasia Group.

“Vietnam has been fully prepared for TPP," according to Dinh Xuan Thao, chairman of the legislature's research institute. "As it decided to join the free trade agreement, it accepted to face short-term difficulties for greater benefits in the long run. The government has informed us about that during the negotiation process. We are united in that regard. Therefore, there should be no hurdles in approving it."

But Thao told VOA there is concern in Vietnam about the rights of state-sanctioned labor unions in the communist country.

Chinese involvement?

A former prominent Vietnamese lawmaker, Nguyen Minh Thuyet, sees the TPP deal allowing Vietnam to have less reliance on its giant northern neighbor and its primary adversary over the centuries.

“Vietnam’s current trade balance is tilted toward China, and major infrastructure contractors in Vietnam are Chinese, so Vietnam relies on China greatly," Thuyet said in a VOA interview. "Joining TPP, Vietnam would have more partners, and that partnership could help Vietnam to reduce its dependence on China in economic terms. It is also a desire of most Vietnamese; but, that requires determination and sound economic policies."

Australia, Brunei, Mexico, Peru and Singapore are also TPP members.

In those countries — where lawmakers and governments are generally seen as favoring global trade — the partnership is eventually expected to be ratified.

A subsequent round is expected to see others lining up for entry.

Most notably, China, the world's second-largest economy, is expressing interest.

“What worries me now is the rhetoric that is suggesting that signing this deal is sort of a blow against China, somehow,” said Elms on Thursday. “That makes it even more difficult to get China in, in the future.”

Thailand is another possible second round entrant, but more likely are Colombia, Costa Rica, Hong Kong, Panama, the Philippines, South Korea and Taiwan.